Kimmeridge oilfield was discovered in 1959

Environmental groups have criticised plans to extract oil and gas from new areas in Dorset.
Piddle Valley, Lytchett Matravers and Corfe Castle are among nine sites suggested by energy companies.

Friends of the Earth activists say the Purbeck coastline is already "fragile" and eroding.
An energy expert said an existing Dorset site was an example of how extraction could be carried out in an environmentally sensitive area.

The Oil and Gas Authority announced last week 27 locations in England where licences to frack for shale oil and gas would be offered.
A further 132 blocks nationally have been subjected to further detailed environmental assessment under EU law, including the sites in Dorset.
'Environmentally sensitive'

The findings of this assessment are now out for public consultation, and more offers for licences will be made later in the year.
Friends of the Earth activist Angela Pooley said she believed investment should be made in renewable energy as well.

"It's a very sensitive area, it's already very fragile, the Purbeck Coast has already seen evidence of erosion," she said.

Joseph Dutton, associate research fellow at the University of Exeter's energy policy group, said any further oil and gas production would be similar to existing Dorset sites, such as Kimmeridge, which have been in use for decades.

He said: "Wytch Farm is the largest onshore producing oil field in western Europe.
"It's an area of outstanding natural beauty and is often held up as an example of how oil and gas can be extracted in an incredibly beautiful and environmentally sensitive area."

Before beginning any exploration and production activity, licensees would have to first obtain consent from the landowner, Environment Agency, Health & Safety Executive and the Oil and Gas Authority.